Curvature-modulated slip effects on flow and heat transfer characteristics in structured microchannels

Efficient thermal management requires microchannel heat sinks with diverse flow-path designs, among which curved microchannels are particularly important and unavoidable in spatially constrained devices. However, heat transfer enhancement strategies based on compound structures in curved microchannels remain less explored than those in straight channels, and the coupling mechanisms are still unclear. Here, we propose a novel approach that integrates slip boundary with rib/cavity microstructures in curved channels and elucidates the curvature-modulated mechanisms governing their coupled thermal-hydraulic response. Four curved configurations with different rib/cavity arrangements: inner rib-outer cavity (IROC), both-side cavities (BC), inner cavity-outer rib (ICOR), and both-side ribs (BR) are compared with straight counterparts. The results show that curvature-induced flow redistribution makes the outer-side structure dominant in determining flow and heat transfer characteristics. Under no-slip conditions, cavity-containing curved channels exhibit better overall performance. Under slip conditions, the performance contribution of ribs increases significantly owing to the substantial reduction in flow resistance. The optimal curved configuration shifts from cavity-dominated BC ( PEC = 1.06 – 1.23), to ICOR ( PEC = 1.80 – 2.01), and to rib-dominated BR ( PEC = 2.13 – 2.21) at the moderate flow rate. These findings reveal the curvature-modulated mechanism by which the slip effect regulates momentum and thermal transport around rib/cavity structures, underscoring the potential of hydrophobic structured microchannels for high-performance thermal management.